Process of agglomerating loose materials



Patented Apr. 28, 1925.

UNITED STATES PATENT OFFICE.

ALBERT L. STILLMAN, OF PLAINFIELD, NEW JERSEY, ASSIGNOR TO THE SMELTERS GENERAL BRIQUETTE CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF AGGLOMERATING LOOSE MATERIALS.

No Drawing.

To all whom it may concern:

Be it known that I, ALBERT L. STILLMAN,

a citizen of the United States of America,

and a resident of Plainfield, county of Union, State of New Jersey, have invented certain new and useful Improvements in Processes of Agglomerating Loose Materials, of which the following is a specification.

My invention relates to the briquetting or agglomerating of various substances and particularly substances that contain oxygen; as examples of such substances I may mention metal oxides, notably oxides of iron or 1 chemical compounds similar in character to oxides, ph sphate rock (apatite) etc. In my present invention I produce a cementing or binding action by means of an agent having both acid or corrosive and gummy or agglutinant characteristics. The medium or agent employed by me must contain two elements or ingredients, one of which is a gummy or glue like ingredient such as would of itself be sufiicient to form a binder in the manufacture of briquettes. The briquettes thus formed would not necessarily be waterproof. As instances of such gummy or agglutiant ingredients I' may mention coal tar pitch, asphalt, sulphite liquor (neutral), ao molasses, dextrin, and glue. The second ingredient is an acid or a saline solution contaiuing an acid radical such as hydrochloric, sulphuric, phenylic, cresylic acid and the like, which by its corrosive action on the as loose material, and in conjunction with the gumn'iy ingredient, will form a cement or binder which is waterproof so that a waterproof briquette will be obtained. I desire it to be understood that acid sulphite liquor 40 is a substance suitable for the purposes of my invention since it contains both the acid or corrosive ingredient and the gummy or agglutinant ingredient required to obtain the results of my present invention.

Heretofore in briquettiug substances of the general character above referred to, it has been necessary to use expensive mold and piston presses of slow and costly operation. The employment of a roll press for briquetting has been highly desirable since such a press will give a large tonnage capacity at small cost. It has, however, been very diflicult heretofore to use the binders formed by chemical reaction and Oxidation, in roll press.

Application filed October 3, 1922. Serial No. 592,166.

press practice. Owing to the fact that briquettes are dropped a relatively considerable distance when leaving the press, and since they are still weak at that time owing to the fact that the chemical reaction has not been completed, the briquettes are generally broken by their fall from the Neutral sulphite liquor, when used alone, or molasses and like substances, are satisfactory so far as their binding properties are concerned but are not available in practice for the reason that they are soluble in water so that briquettes made with them must be kept under cover at all times and must not be exposed to moisture. This handicap has been suflicient to prevent any extended use of metallurgical briquetting with binders of this character.

Now, according to my invention, I employ an agent which not only contains a gummy ingredient, but in addition thereto an acid or a salt of an acid. In this case a chemical reaction will occur in the briquette and this chemical action will result in permanent and waterproof setting; a gummy binder practically fulfills only the function of holding the briquette together during its fall from the roll press after its formation and during the handling that occurs immediately thereafter. I am aware that waterproof briquettes can be made by the use of certain gummy ingredients alone (without any acid ingredient) such as coal tar, coal tar pitch and asphaltic oils; but in these cases unless the pitch is extremely hard (and in that case there are insuperable melting and briquetting difficulties) the briquettes will soften under conditions of summer heat and will frequently run t ogether when loaded into cars. These drawbacks, however, are avoided if, according to my invention, an acid or a salt of an acid is present together with a gummy substance in the agent with which the loose material to be briquetted is mixed.

When applying my invention to the briquetting of blast furnace flue dust which preferably should be used fresh, that is to say when it contains an appreciable amount, for example, ten per cent or not less than seven per cent. I may proceed as follows The loose material to be briquetted is mixed for instance in a paddle mixer and edge mill with the agent containing, as above set forth,

a gummy ingredient and an acid or acid salt ingredient. For instance, I may employ sulphuric acid as the acid ingredient 1n the proportion of about one part of sulphuric acid of 60 B. and five parts of water. As the gummy ingredient I may employ coal tar or coal tar pitch in the proportion of from four to fifteen per cent. of the loose material, ten per cent. being generally suitable. An appropriate proportion of loose material (blast furnace flue dust) gummy ingredient and corrosive ingredient is ninety parts loose material, eight to nine and threefourths parts gummy ingredient and two to one-fourth parts corrosive ingredient. The mixture is passed through a roll press and the briquettes are made thereln in the well known manner. A chemical reaction takes lace between the sulphuric acid and the ferrous oxide of the blast furnace flue dust which may be expressed by the equation:

About simultaneously the following additional equations take place:

The iron sesqui-oxide thus formed both during the mixing operation and durmg and after the briquetting, forms of Itself a cement of strong binding action and also combines with the coal tar or other gummy ingredient employed to form an extremely strong cement which resists successfully any normal weather condition. In this case, therefore, the corrosive ingredient serves to make the easily melted binders, such as the coal tar, resistant to heat. If, however, the gummy ingredient is one that is soluble in water (for instance, molasses or the gum contained in neutral sulphite liquor) the use of the corrosive ingredient serves to make the water soluble binder insoluble or waterproof in the briquettes.

In case any acid salt (for instance iron sulphate) is mixed in the solution with any gum such as molasses, the reaction occuring with blast furnace flue dust, or rather with the FeO which is the active principle of such flue dust, is as follows It will be understood that in each case the iron sesqui-oxide forms the hard, waterproof binder desired.

It will be understood that I do not wish to be restricted to the examples given above. Thus, instead of sulphuric acid, I may employ others and particularly I may make use of coal tar or coal tar pitch containing certain tarry acids, for instance, phenylic glomerating loose material,

and cresylic; acids, these acids acting on the IIOll monoxide 1n the same manner that has been set forth above with reference to sulphuric acid. It will also be understood that as the corrosive ingredient of the medium or agent employed by me I may use any acid or salt capable of corroding FeO to Fe O and contained in, or mixed with, a gummy or pitchy substance in such form that the above reactions will occur.

The briquettes are allowed to set and harden after they have been discharged from the press, and are preferably subjected to a gentle current of air to hasten this hardening action. For instance, the briquettes may be deposited on a slowly moving conveyor belt.

While I do not wish to confine myself to any particular size of briquettes, it will be generally preferred to make the briquettes as small as is consistent with the operation for which they are required (about 5 ounces will be satisfactory in most cases) Various modifications may be made Without departing from the nature of my invention as set forth in the appended claims.

I claim:

1. The herein described process of agcontaining an appreciable amount of FeO which consists in adding to such material an agent having both agglutinant and corrosive characteristics with respect to such material, and then compacting the mixture by pressure.

2. The herein described process of agglomerating loose material, containing an appreciable amount of FeO which consists in adding to such material an agent having both agglutinant and corrosive characteristics with respect to such material, and then compacting the mixture by pressure, while the reaction between said agent and said material is going on.

3. The herein described process of agglomerating loose material, containing an appreciable amount of FeO which consists in adding to such material an agent having both agglutinant and corrosive characteristics with respect to such material, and then compacting the mixture by pressure, while the reaction between said agent and said material is going on, and then exposing the coherent bodies formed by compacting the mixture, to a gentle current of air.

4. The herein described process of agglomerating loose material, containing an appreciable amount of FeO which consists in mixing such material with an agent containin an agglutinant ingredient and another lngredient that will produce a binder by reacting with said material, and compacting the mixture by pressure while such reaction is going on.

The herein described process of agglomerating blast furnace flue dust containing at least 10% of FGO WhiCh consists in mixing "such flue dust'with an agent containing an agglutinantingredient and another ingredient of corrosive character, that will produce a binder by reacting with such flue dust, and compacting the mixture by pressure while such reaction 1s going on.

6. The herein disclosed process of agglomerating blast furnace flue dust While in a fresh condition and containing an ap-.

my hand.

ALBERT L. STILLMAN. 

